LAWRENCE – The fourth week of testimony in the murder and arson trial of Lynn grandmother Kathleen Hilton ends today with more defense witnesses expected in Superior Court on Monday.Hilton, 62, stands charged with torching a triple decker at 44-46 High Rock St. in Lynn on Feb. 24, 1999. Five people living on the top floor were killed.According to Essex County Assistant District Attorney Marcia Slingerland, Hilton set fire to the building because it was home to Krystina Sutherland, who has two children with Hilton’s son, Charles Loayza. The prosecution has contended that Hilton hoped to destroy the building, which would force Sutherland to return to Loayza with the children.Defense lawyer Michael Natola has theorized to the jury that Loayza may have set the fire, adding that Hilton loved her grandchildren and had no reason to harm them, while Loayza had already violated a court restraining order by going to the address.The five victims were not involved with Hilton or others. They were Heriberto Feliciano, 34, and his wife, Sonia Hernandez, 32; their daughters, Sonia, 12, and Maria, 13, and their niece, Glorimar Santiago, who was sleeping over. Hilton has spent the past 10 years behind bars..The trial began Jan. 12.”The fourth week of the trial ends on Friday. The commonwealth has rested its case and the defense has been calling witnesses,” said Carrie Monahan, spokesman for the Essex District Attorney’s Office. “The trial is expected to continue on Monday with more defense witnesses..”Judge Howard Whitehead is presiding. Fifteen jurors are hearing the case.